Ensure for cleanup in Ruby - Mini Project: Build & Apply

Using Ensure for Cleanup in Ruby

📖 Scenario: Imagine you are writing a small Ruby program that opens a file, writes some text, and then closes the file. You want to make sure the file is always closed, even if something goes wrong while writing.

🎯 Goal: You will create a Ruby program that uses begin, rescue, and ensure blocks to handle errors and always close the file.

📋 What You'll Learn

Create a variable called file that opens a file named example.txt for writing.

Create a variable called text_to_write with the value 'Hello, Ruby!'.

Use a begin block to write text_to_write to file.

Add a rescue block to catch any exceptions and print 'An error occurred.'.

Add an ensure block that closes the file.

Print 'File closed.' after the ensure block.

💡 Why This Matters

🌍 Real World

In real programs, files and other resources must be closed properly to avoid problems like data loss or locked files. Using <code>ensure</code> helps keep your program safe and clean.

💼 Career

Understanding error handling and cleanup with <code>ensure</code> is important for writing reliable Ruby programs, which is a valuable skill for software developers and engineers.

1

Open the file and prepare text

Create a variable called file that opens a file named example.txt for writing using File.open. Then create a variable called text_to_write and set it to 'Hello, Ruby!'.

Ruby

# Open the file and prepare the text
# Your code here

Need a hint?

Use File.open('example.txt', 'w') to open the file for writing.

2

Start the begin block and write to the file

Add a begin block. Inside it, write text_to_write to file using file.write(text_to_write).

Ruby

file = File.open('example.txt', 'w')
text_to_write = 'Hello, Ruby!'

begin
  # Write text to the file here
  # Your code here
end

Need a hint?

Use begin to start the block and file.write(text_to_write) to write.

3

Add rescue block to handle errors

Add a rescue block after the begin block. Inside it, print 'An error occurred.' using puts.

Ruby

file = File.open('example.txt', 'w')
text_to_write = 'Hello, Ruby!'

begin
  file.write(text_to_write)
rescue
  # Print error message here
  # Your code here
end

Need a hint?

Use rescue to catch errors and puts to print the message.

4

Add ensure block to close file and print confirmation

Add an ensure block after the rescue block. Inside it, close the file using file.close. Then print 'File closed.' using puts.

Ruby

file = File.open('example.txt', 'w')
text_to_write = 'Hello, Ruby!'

begin
  file.write(text_to_write)
rescue
  puts 'An error occurred.'
ensure
  # Close the file and print confirmation
  # Your code here
end

Need a hint?

Use ensure to always run code, close the file with file.close, and print the message.